High speed apparatus for recording intelligence



United States Patent 6 HIGH SPEED APPARATUS FOR RECORDING INTELLIGENCE John E. Ciemens, Xenia, and Ben B. Johnstone, Dayton, Ohio Application April 18, 1952, Serial No. 283,108

2 Claims. (Cl. 346--74) (Granted under Title 35 U. S. Code (1952), sec. 266) The invention described herein may be manufactured and used by and for the Government for governmental purposes without the payment to us or to either of us of any royalty thereon.

This invention relates to an apparatus for recording intelligence of a transient nature, for example, voltage values produced on the screen of a cathode-ray tube. The invention is broader than that, however, since the method and apparatus are capable of recording any intelligence which is capable of being produced from an electrical signal.

One object of the invention is to produce a recording apparatus and method in which the use of inks, with their manifold objections, is entirely avoided.

Another object of the invention is to produce an apparatus and method which is capable of a much higher speed of recording than any heretofore known.

Another object of one form of the invention is to provide an apparatus and method in which the transfer of intelligence from a cathode-ray tube to a strip of paper takes place merely by contact without any auxiliary apparatus between the two elements.

Briefly stated, this invention rests upon the combination of the photographic process known as Xerography with the discovery that localized charges sufficient for the conduct of the xerographic process can be transferred by partial discharge of a previously charged moving surface directly from a cathode-ray tube to a nonconducting paper. Such transfer takes place by running the paper strip in electrical contact with or exposed to a light beam from the face of the tube while a one axis time-variable voltage presentation is being applied to the screen thereof. The remaining part of a simplified form of the process comprises subjecting the paper strip and its isolated static charges to the xerographic process or modifications thereof. This process is the invention of Chester F. Carlson and has been fully disclosed in Patents 2,297,691 and 2,357,809 and described in the Journal of the Optical Society of America, volume 38, No. 12, pages 991998, December 1948.

This invention, therefore, makes use of the fact that an electrostatic charge carried on the paper tape may be used to attract a pigmented powder which can then be permanently aflixed to the paper by fusion. This invention provides a direct-reading permanent record capable of higher frequency response than has been possible for any other direct recording device. It is, in fact, capable of matching the performance of photographic recording without its disadvantage of processing delay. By recording one scanning line at a time from a television raster, the way is open for the permanent recording of television programs. It is, of course, evident that the sensitized paper strip employed might bear a border of magnetic tape by which a synchronized sound program could be recorded.

Referring now to the accompanying drawings,

Fig. 1 is a perspective view of a preferred form of the invention, which, however, necessitates a special cathice ode-ray tube detailed by section and by fragmentation in Figs. 4 and 5 respectively;

Fig. 2 is a perspective view of a modified apparatus in which a conventional form of cathode-ray tube may be employed. Part of this apparatus is broken away to show the interior of a powder container;

Fig. 3 is a schematic representation of a modification of the device in Fig. 2 in which a transparent adhesive tape is used for the fixing of the image which is in the form of distributed powder on a cellophane strip. The use of heat for fixing is thus avoided;

Fig. 4 is a detail of the cathode-ray tube shown in Fig. 1, the detail showing the preferred means employed for electrically charging the paper strip. It is taken along the line 4-4 of Fig. 1;

Fig. 5 is a detail of Fig. 4 showing how individual charging termini or contacts are obtained by cutting the wire coating of a wound insulating spindle.

Referring now to Fig. 1, 10 is a cathode-ray tube, the screen part of which is narrowed down to a rectangle 11 which is in contact with a paper strip 12. The paper strip is originally stored on a roll 13 from which it passes over an idling drum 14 under the influence of a driving drum 15, a motive power of which is not shown. The record, which is the chief goal of the invention as shown, is 16 on that part of the paper strip 12 which is subject to the roll 15.

The cathode-ray tube it) has a pair of conventional deflection plates 17 vertically disposed in the tube neck whereby a stream of electrons from an electron gun (not shown) may be horizontally scanned over an array of fine wire termini 18. A cross section of this array is shown in Fig. 4. In that figure the front glass wall of the tube it) is indicated by 19 and the paper strip by 12. Contact is obtained at the apex of a triangle, which is the cross-sectional form of a glass spindle 21 about which a coil 22 (see Fig. 5) was originally wound. After winding, the coil 22 was cut at 23 on the rear face of the triangle. The entire array was fused into the front face of the rectangular portion 11 of the tube 10 and the glass ground away from the apex 20 so that a large number of separate similar triangles of wire extend from the interior face of the cathode-ray tube to the paper strip 12. It will be evident, therefore, that the charge of an electron beam impinging upon the rear race of the array 18 will be conducted through the individual wire triangles to the nonconducting paper strip 12 upon which a localized static charge will be deposited. This charge will be governed as to value and location by the transient voltage and positional condition of the electron beam at the time that it impinges any individual wire triangle of the array 18.

It is obvious that some way of discharging the individual wire triangles of the array 18 must be provided so as to have these in a receptive condition for an additional charge each time that the cathode-ray beam impinges upon them. The grounding is accomplished by coating the lower rear face of the array 18 with a high resistance conducting composition 24. Preferably a scratch (not shown) is made in this composition between each wire triangle. Each individual plaque 24 of coating is grounded by contact with a grounding strip which is disposed horizontally along the lower part of the plaques 24 and is represented by the ground symbol 25.

Again referring to Fig. 1, 2-6 is a belt driven by a roll 27 whereby tribo-electric powder 28 is brought in thin layer form against the charged surface of the paper strip 12 after contact with the charging array 18. As is well known, from the teachings of Carlson, above referred to, the tribe-electric powder 2 8 disposes itself on the charged areas to form an image which can then be fixed by heating to the fusion or sintering temperature of the powder. In Fig. 1 the drum 14 is preferably heated to such a temperature as to be able to fuse the powder 28 without being able to scorch or materially weaken the paper strip 12. It is optional, however, whether the heating be applied by roll 14 or roll 15.

Referring now to Fig. 2, 30 is a drum preferably made of aluminum or other light highly conductive metal. The drum is coated with a first coating of elemental selenium, with a proportion of sulfur, as set forth in the Carlson patent referred to. This coating is not shown because it is very thin. It is, of course, light-sensitive, since this is the well known property of selenium. Over the selenium coating there is a very thin sprayed coating of a synthetic resin plastic, which may be methyl methacrylate. The plastic coating has the function of protecting the selenium and of holding static charges long enough to accomplish the purposes of xerography. symbolically indicated in dashed line is the screen 31 of a cathode-ray tube. tube It The drum 30 is provided with a brush-discharge charging device 32 immediately before the charged area is subjected to photon bombardment through a conventional phosphor tube screen 31. To accomplish this, the drum is rotated in a counterclockwise direction by power means, not shown, but, of course, a different disposition by the apparatus may render clockwise rotation preferable. The charged plastic surface becomes discharged under the illumination provided by the cathode-ray tube according to the intelligence impressed by modulation on the electron beam. A condensing lens system (not shown) may be employed between the screen 31 and the drum 3%). Consequently the plastic surface is irregularly discharged to form various localized electrostatic areas, the voltage of which is able to convey the intelligence impressed upon the electron beam and conveyed by the light beam from the screen 31 to the surface of the drum 30. These electrical charges endure while the drum 30 is rotated counterclockwise to an angular position at which a tribo-electric powder 33 contained in a box 34 is elevated by a small power-actuated lifting conveyor 35 and dumped upon a downwardly inclined surface 36 which makes contact with the drum surface. The level of the powder 33 upon the inclined surface 36 is regulated by a doctor blade 37. An auxiliary doctor blade makes contact with the drum 30 to level off any inordinately high accumulations of powder upon the drum surface. The drum has now attached to its a powder coating, the thickness of which is an index of the extent and potential of the static charges deposited by the charger 32 and modulated by the light beam from the screen 31. The next step is to transfer this powder bodily to a paper strip 12 without disturbing its orientation any more than nec essary. To this end, the strip 12 is drawn from a roll 38 over an idler roll 39 which is in contact with the drum 30. The strip 12 makes arcuate contact with the drum 30 under an electrical brush discharge 40, thereby picking up the oriented powder from the plastic surface. Heat is then applied to fix the powder to this paper. A second idler roll 41 enables the strip 12 to be separated from the .drum and wound upon a storage roll 42. The pat tern 16, in this case a voltage wave, is now fused to the strip 12 and provides a permanent record. Between the charger 32 and the idler roll 41, there is placed in contact with the drum surface 30 a cleaning roll 43, the surface of which has a mild cleaning action so that any vestiges of untransferred powder may be removed from the drum by rotation of the roll 43 before another cycle of operation takes place.

Referring now to Fig. 3, 19 is the face of the cathoderay tube, the electron beam from which is directed through a condensing lens system 44 to the face of the drum 30 through a paper strip, which in this case is trans- The tube is arranged to scan horizontally like the parent. Cellophane is a suitable material for the strip 12 in this instance. The drum rotates counterclockwise as before and is provided on its opposite side with the same apparatus 32, 34, 35, 36 and 38 for applying a triboelectro powder 33 to the strip 12 after it has received static charges which are modulated by the light beam passing through the lens system 44. The strip 12 is wound upon a power driven roll 42 after having applied to its image carrying face a transparent strip 46 from a storage roll 45. The strip 46 is the resin coated cellophane tape known as Scotch Tape. The adhesive coated side is applied by pressure roll 47 to the powder-coated face of the strip 12 to fix and preserve the image thereon. This image may of course be observed because both the strip 12 and the strip 46 are transparent. By this mode of fixing the image, the use of heat is made unnecessary.

Numerous changes in the above described invention or inventions may be made within the scope of the appended claims. One such change is the substitution of electromagnetic electron beam control means form the electrostatic deflection plates 17 shown in Fig. 2. Each is the full equivalent of the other. Electromagnetic means for controlling such means are well known. Other chemicals such as anthracene may be substituted for selenium to coat the drum. Dye-colored image developing and fixing powders are the equivalent of pigmented powders.

We claim as our invention:

1. For use in a recording device a charge transfer device comprising an evacuated cathode ray tube having a single presentation glass face and means to scan a cathode ray in a substantially straight line across said face, a plurality of substantially parallel Wire triangles imbedded in said glass face with the bases of said triangles arranged inwardly of said face and the apices projecting outwardly of said tube to make mechanical contact outside of said tube, said bases of said wire triangles being discontinuous intermediate the ends thereof to provide first and second base portions, a first portion of each of said bases being aligned to be impinged by said cathode ray to receive a charge therefrom, the divergent side portions of said wire triangles between said base portions and said apices being sealed in said glass face, a ground conductor, individual connectors between said several second base sections and said ground conductor, said individual connections being composed of high resistance conducting material.

2. A recording device comprising an evacuated cathode ray tube having a signal presentation glass face and means to scan a cathode ray in a substantially straight line across said face, a plurality of substantially parallel wire triangles imbedded in said glass face with the bases of said triangles arranged inwardly of said face and the apices projecting outwardly of said tube for making mechanical contact outside of said tube, said bases of said wire triangles being discontinuous intermediate the ends thereof to provide first and second base portions, a first portion of each of said bases being aligned to be impinged by said cathode ray to receive a charge therefrom, the divergent side portions of said wire triangles between said charge pattern produced on said strip.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Bruce Feb. 17, 1942 6 Bruce May 12, 1942 Kernkamp July 28, 1942 Tolson Mar. 13, 1951 Carlson Ian. 6, 1953 Grey Oct. 27, 1953 Huenber Sept. 6, 1955 

